Language that uses [t] (or [k]?) in formal settings and [k] (or [t]?) in in informal

Question

I remember reading about some language in which both [t] and [k] were considered the same phoneme and one of the [t] and [k] were used in formal and the other in informal settings. Does such a language exist or was what I read a myth? I apologize for being vague but I have no other information about that language and it is bugging me.

Answer 1

There are a few Polynesian languages such as Hawaiian and Samoan that don't contrast [t] and [k] i.e. [t] and [k] exist as allophones of /t/.

The language you're looking for seems to be Samoan where /t/ is pronounced [k] in colloquial speech and [t] in formal speech.

Answer 2

K (Depending on the person) is used in everyday speech, though T is used to greet people formerly. So, T is replaced with K, similar to how Tongans replace the sound of their Ts with a D, but in Samoa you can choose to speak which ever style you like depending on the situation.